1. Field of the Invention
The present invention relates to logic and methods for signal-independent power consumption to withstand differential power analysis and other side-channel attacks.
2. Description of the Related Art
Electronic banking, e-commerce, virtual private networks and so on cannot operate without encryption technology and a secure implementation of the encryption technology. To obtain security, many strong encryption algorithms have been developed. While usually strong against mathematical attacks, Side Channel Attacks (SCAs) can reveal the secret key through information leaked by the hardware implementation of the encryption module. Differential Power Analysis (DPA) is based on the fact that logic operations have power characteristics that depend on the input data. Statistical analyses of measured power traces can be used to link the switching activities of the circuit to the secret key.
Different techniques have been tried to prevent this information leakage. On the algorithmic level, random process interrupts interleave dummy instructions to avoid sequential execution of the algorithm. Integration techniques, however, are able to resynchronize the power traces. Masking is a technique that prevents intermediate variables from depending on the knowledge of an easily-accessible subset of the secret key. DPA has been modified to handle masking. On the architectural level, techniques include adding random power consuming operations and duplicating logic with complementary operations. These procedures merely lower the side channel information and might easily be disabled through tampering. Active power signal filtering with power consumption compensation, passive filtering, battery on chip and a detachable power supply influence the power transfer itself. The first method lags behind the fast power fluctuations and physical dimensions limit the latter three.
None of the above methods provide satisfactory protection against attacks based on DPA.